This invention relates to a flywheel slip clutch for preventing damage to an implement, such as an agricultural baler.
Current practice in agricultural balers is illustrated in FIG. 3 where a flywheel a is rotatably mounted on the input shaft b of the transmission gearbox c. A hub d is fixed to the end of the gearbox input shaft b by splines, and the hub d and flywheel a are connected together by a shearbolt e designed to fail at a preselected torque limit. The tractor PTO drive line f and clutch g are typically connected directly to the flywheel a so that the tractor PTO torque is routed through the PTO drive line f and clutch g to the flywheel a, then through the shearbolt e to the hub d, and then into the gearbox input shaft b. This method while effective has some drawbacks. For example, the shearbolt failure torque must be high enough to prevent nuisance failures of the shearbolt e. The shearbolt e is subject to fatigue failures from repeated cycles of loading. When an overload condition occurs causing failure of the shearbolt e, the operator must shutdown operation of the baler in order to replace the shearbolt e and frequently must manually clear out the feeder to prevent an additional shearbolt failure due to the overload condition. The shearbolt e does not typically give any warning or indication that an overload condition is being approached.
The present invention eliminates the shearbolt e in a manner that causes the tractor PTO drive line f and the flywheel a to be additive in torque. This reduces the amount of torque required from the flywheel a while still providing adequate torque to the input shaft b of the transmission gearbox c. In operation, the torque available to the gearbox input shaft b from the flywheel a can be lower because shearbolts must be designed to fail at a high enough torque to prevent nuisance failures. The present invention also gives advance warning of impending overload conditions by the flywheel a starting to slip out before the tractor PTO clutch g disengages. This advance warning and the elimination of the necessity to shutdown operation to replace a shearbolt gives operators confidence to operate balers at a higher capacity.
The present invention provides a flywheel slip clutch for connecting a flywheel to an input drive shaft of an implement. The flywheel slip clutch comprises a plate connected to rotate the input drive shaft and adapted for connection to a tractor PTO drive line and clutch, the flywheel being rotatably mounted on the input drive shaft, and friction means interposed between the plate and the flywheel for drivingly engaging and disengaging the plate and the flywheel. In the event of an overload condition on the input drive shaft, the plate and the flywheel are drivingly disengaged and the tractor PTO clutch also disengages. In order to provide warning of an impending overload condition, the plate and the flywheel start to drivingly disengage before the tractor PTO clutch disengages.